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Discussion Starter · #1 ·
I have a 2011 Impreza sti with 69k miles on it and long story short I bought a Cobb tuner for the car to mess with it a little and ended up frying the tune on the car. I took it to my local Subaru tuners and they told me I have bad compression in my cylinders. Cylinder 1 is 135 while cylinder 4 is 120 psi. They told me if they were to tune and dyno the car that it would have blown up trying to dyno, so they told me they won’t even do it. Instead they put a break in tune on my car so when I rebuild the motor I slap in the motor, break it in and then go back to them to tune it properly. Now my mission is to rebuild this motor correctly with the right parts such as fordged pistons and have my arp head studs and head gasket as well replaced and made sure it won’t go out. This is my first Subaru and first sports car to work on and fix but I need help trying to figure out the safest route as well as be safe with money cause parts are very expensive. I want to know advice with rebuilding these motors as well as knowing what’s the best part to put like what company either Manley or arp etc. I’m just a little lost on where to start with the car rebuilding wise and how I should start tackling the car itself with trying to pull out the motor. If anyone can give me suggestions about any information on my car and what to do and what not it would help me most. after market engine internals to externals like air oil separator and Evap system light on that would be great
 

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Seems like you're all over the place here. I would highly suggest you have 1 shop do everything. Remove, rebuild, install, and tune. The most common and usually highly recommended thing to do when going for a rebuild project is to go with an IAG short block. I would also suggest you speak with you tuner on your goals about all of this.
 

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ok so you need to answer a few questions. what are your power goals for the car? need to know this to know what motor to suggest.
did YOU fry the tune? like did you try to retune it? cause if you didnt you probably didnt cause the issue. but if you attempted to adjust the tune yeah likely your fault. no worries though.
i'd absolutely tell you to have a shop do everything. just to make sure it's done right. building these motors can be somewhat done in a garage. but to properly do a valve job and balance the shortblock, you need tools that are insanely expensive. so much so that some companies buy motors from others to not pay for these tools.

if you are anywhere near MD, go to IAG motorsports, or try to find a local place that is a certified IAG installer. and if you want anything over stock turbo power levels, get an IAG shortblock. pending goals, an oem rebuild on the heads will likely be all you need. if you only want stock turbo power levels you can get a subaru oem type RA block and be ok.
 

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Discussion Starter · #4 ·
Seems like you're all over the place here. I would highly suggest you have 1 shop do everything. Remove, rebuild, install, and tune. The most common and usually highly recommended thing to do when going for a rebuild project is to go with an IAG short block. I would also suggest you speak with you tuner on your goals about all of this.
 

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Discussion Starter · #5 ·
Okay thank you. Yeah I just haven’t found time to focus 100% on the car itself. I have work and school that I’m juggling atm and it’s summer time too so fun comes with it lol. I was planning on doing it myself just because it’s cheaper and I’d really wanna know the knowledge behind this stuff aswell and googling it isn’t gonna tell me everything. But yeah I think the best option would be to have a shop do it for me since I can’t get to it myself and trust that I won’t screw up
 

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Discussion Starter · #6 ·
ok so you need to answer a few questions. what are your power goals for the car? need to know this to know what motor to suggest.
did YOU fry the tune? like did you try to retune it? cause if you didnt you probably didnt cause the issue. but if you attempted to adjust the tune yeah likely your fault. no worries though.
i'd absolutely tell you to have a shop do everything. just to make sure it's done right. building these motors can be somewhat done in a garage. but to properly do a valve job and balance the shortblock, you need tools that are insanely expensive. so much so that some companies buy motors from others to not pay for these tools.

if you are anywhere near MD, go to IAG motorsports, or try to find a local place that is a certified IAG installer. and if you want anything over stock turbo power levels, get an IAG shortblock. pending goals, an oem rebuild on the heads will likely be all you need. if you only want stock turbo power levels you can get a subaru oem type RA block and be ok.
 

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Discussion Starter · #7 · (Edited)
Yeah most likely the plan will be to ride till she blows and take it to my local tuner shop. Where I’m located at in Illinois there is a tuner shop specifically for Subarus and they told me what I should do to the block if I was going to rebuild it but they suggested I drive it till she blows and then take it there for a rebuild. They are gonna charge expensive as they said it would be due to the amount of work it needs. I didn’t fry the tune and I’m thinking to have 400 hp by the time is rebuilt. I was given the car for a graduation present and the tuner shop told me there’s over 10k in after market parts installed on the car like all intake manifold parts are Perrin and the down pipe along with exhaust is Perrin. It has an e85 Cobb fuel system installed, so the previous owner was trying to make near 400 hp range. The turbo isn’t stock and I can’t seem to figure out what brand it is just cause the model number brings up a Cobb turbo. It’s not a Cobb cause it says nowhere on the turbo itself that it’s Cobb.
 

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Yeah most likely the plan will be to ride till she blows and take it to my local tuner shop. Where I’m located at in Illinois there is a tuner shop specifically for Subarus and they told me what I should do to the block if I was going to rebuild it but they suggested I drive it till she blows and then take it there for a rebuild. They are gonna charge expensive as they said it would be due to the amount of work it needs. I didn’t fry the tune and I’m thinking to have 400 hp by the time is rebuilt. I was given the car for a graduation present and the tuner shop told me there’s over 10k in after market parts installed on the car like all intake manifold parts are Perrin and the down pipe along with exhaust is Perrin. It has an e85 Cobb fuel system installed, so the previous owner was trying to make near 400 hp range. The turbo isn’t stock and I can’t seem to figure out what brand it is just cause the model number brings up a Cobb turbo. It’s not a Cobb cause it says nowhere on the turbo itself that it’s Cobb.
yeah i'd save for a motor. expect if youre going to build it to be in the 10k ish range for everything.

as far as the turbo, it could be a cobb based on the part number. it's rare to see but someone could have had the turbo rebuilt/ported/upgraded and had the cobb logo they usually have on the compressor housing filed off and then repainted/powdercoated. cobb does only make a 20g turbo to my knowledge. which, on e85, would be enough to make 400whp on most dynos. if you are worried about the turbo you could always buy a different one or send it out to a company that can rebuild/upgrade them.

also, i wouldnt wait until it blows. if it's not blown and you dont have any flakes in your oil, you could get away without having to replace all the oiling lines and inspecting the turbo for possible damage, if you decide to wait until it blows, you'll want to replace every bit of oiling you can, to ensure that you dont have any flakes that could damage the new motor.
 

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Discussion Starter · #9 ·
yeah i'd save for a motor. expect if youre going to build it to be in the 10k ish range for everything.

as far as the turbo, it could be a cobb based on the part number. it's rare to see but someone could have had the turbo rebuilt/ported/upgraded and had the cobb logo they usually have on the compressor housing filed off and then repainted/powdercoated. cobb does only make a 20g turbo to my knowledge. which, on e85, would be enough to make 400whp on most dynos. if you are worried about the turbo you could always buy a different one or send it out to a company that can rebuild/upgrade them.

also, i wouldnt wait until it blows. if it's not blown and you dont have any flakes in your oil, you could get away without having to replace all the oiling lines and inspecting the turbo for possible damage, if you decide to wait until it blows, you'll want to replace every bit of oiling you can, to ensure that you dont have any flakes that could damage the new motor.
 

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Discussion Starter · #10 ·
Yeah that seems like the safest route. I was wondering if waiting till it blows would be a good idea but obviously not. the only reason I was gonna do that is cause it's my daily driver and for money purposes too. But i want to keep it reliable and fast at the same time. But in the near future, I am planning on making all internals forged and ready for some scary hp. Ofc I need to learn a little about what im dealing with here. But I appreciate it Karlot, thank you. Sick Hawkeye btw its sexy as fuc.
 

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Yeah that seems like the safest route. I was wondering if waiting till it blows would be a good idea but obviously not. the only reason I was gonna do that is cause it's my daily driver and for money purposes too. But i want to keep it reliable and fast at the same time. But in the near future, I am planning on making all internals forged and ready for some scary hp. Ofc I need to learn a little about what im dealing with here. But I appreciate it Karlot, thank you. Sick Hawkeye btw its sexy as fuc.
thanks man. i appreciate it. i'm working on getting it wrapped and finally looking good. follow my journal on here if you wanna see where i take the build as time goes on

(currently planning a wedding so it's a bit slow at the moment)

also, if you stay at a reasonable power/boost level, it would be cheaper to get a type ra block. they will easily hold mid 300s and on ethanol have held much more. it's an oem block and you can use that on a lower power setting till you build the one you pull out, just a thought.
 

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I would also suggest that while you save up and deal with life and such you also make sure you are extra careful on routine maintenance and don't push the car to it's limits in the meantime. Last thing you want is to help the motor jump off the cliff lol. I agree with Karlot don't wait till it is blown because you won't want to risk a new motor with a lot of stuff that might just make it blow again if something gets missed or spending a lot extra for replacing things you might not have to. I pretty much decided to replace all the things when I built because I am anal and wanted to just do it right once. 🤓
 

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Discussion Starter · #13 ·
I would also suggest that while you save up and deal with life and such you also make sure you are extra careful on routine maintenance and don't push the car to it's limits in the meantime. Last thing you want is to help the motor jump off the cliff lol. I agree with Karlot don't wait till it is blown because you won't want to risk a new motor with a lot of stuff that might just make it blow again if something gets missed or spending a lot extra for replacing things you might not have to. I pretty much decided to replace all the things when I built because I am anal and wanted to just do it right once. 🤓
 

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Discussion Starter · #14 ·
Thanks man I appreciate it, I will make sure I won't destroy the car lol. I keep it's normal maintenance for it and I don't drive it that much, only when I have too.
 

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Discussion Starter · #15 ·
thanks man. i appreciate it. i'm working on getting it wrapped and finally looking good. follow my journal on here if you wanna see where i take the build as time goes on

(currently planning a wedding so it's a bit slow at the moment)

also, if you stay at a reasonable power/boost level, it would be cheaper to get a type ra block. they will easily hold mid 300s and on ethanol have held much more. it's an oem block and you can use that on a lower power setting till you build the one you pull out, just a thought.
 

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Discussion Starter · #16 ·
I will man I will. Thank you for the advice btw its given me a clear conscious about it. Congrats on getting engaged that's crazy! I will definitely follow your pages.
 

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I will man I will. Thank you for the advice btw its given me a clear conscious about it. Congrats on getting engaged that's crazy! I will definitely follow your pages.
thank you.

and yeah no problem. if you have any questions feel free to reach out.
 

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am i missing something?

they did a compression test on your car but said cylinder 1 was at 135, but cylinder 4 was at 120? what were the others?

where do you live? Because my OEM engine, and built engine compression tested at 120 across all 4 and I live in Denver.

I suggest making sure you actually do have low compression, because both times I had low compression in a cylinder it was 60 psi.
 
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